imagine that we have 2 processes: 1 and 2, process1 wants to go to the CS: Let's start with the first process: Repeat flag[1] := true; turn := 2; I want to explain the "while" in your code: if falg[2] was equal to true: it means that the the process2...

Both of your thread is doing following steps: Lock Long empty loop Print Unlock Lock Long empty loop (and so on) Practically, you haven't left any time for context switching, there is a lock just right after the unlock. Solution: Swap the "lock" and the "long empty loop" steps, so...

Yes, that is true because volatile write happens-before written value can be read from the variable. Not exactly. There is a guarantee that another thread synchronized on the same monitor will see the updated value, because monitor release happens-before same monitor acquire by another thread. Without acquiring the same...

Ok I had indeed not fully understood your requirements, sorry about that. Below you'll find a different approach which relies on subscribers signalling that they are done via dedicated subjects. These subjects are then zipped together: this gives you the "lock" semantics (note that overloads of the Zip operator support...

You are essentially describing a ReadWriteLock. Every two methods are allowed to run simultaneously (a "read lock"), except for master(), which excludes all others (a "write lock"): public class MyClass { private final ReadWriteLock rwLock = new ReentrantReadWriteLock(); private final Lock r = rwLock.readLock(); private final Lock w = rwLock.writeLock();...

The two cases are completely different. When you use synchronized, a lock (monitor) is obtained on the object that is passed as argument. synchronized(this) --> Thread obtains lock on "current" object. synchronized(iface) --> Thread obtains lock on "iface" object Will the net effect be the same? No, the effects could...

You must take the value of the variable when atomicAdd read the memory, after atomicAdd is executed another thread can access the memory and modify it. int localIndex = atomicAdd(&(position), (int)1); Result[localIndex] = tableOfArrays[idx][i]; ...

the cpu will wait for the commands before Volatile.Write(ref m_flag, 1); before starting to write to m_flag? Eeeh, kinda. A better way to phrase this is: it's guaranteed that, if any other thread sees m_flag set to 1, they will also see m_value set to 5. And how is...

Yes it is the only way. private synchronized myMethod() { // do work } is equivalent to: private myMethod() { synchronized(this) { // do work } } So if you want to synchronize on an other instance than this, you have no other choice but declaring the synchronized block inside...

Why is the output not synchronized, how to make it run synchronized? The output is synchronized. Each line is complete and correct. If it were not synchronized, you would see some lines inside another line. I assume you mean; how can I hold a lock for the whole loop?...

i = 1 always happens-before v = 2 True. By JLS section 17.4.5, If x and y are actions of the same thread and x comes before y in program order, then hb(x, y). v = 2 happens-before vDst = v in JMM only if it's actually happens before...

Akka ideology is 'let it crash', so it's best to isolate potentially dangerous functionality into a separate actor. How i would do that - sample actor hierarchy: /master /validator /authentication /capability /registrar /widget1 /widget2 /widget3 Assuming that you may want to have more functionality in your registrar other than register/unregister...

Akka doesn't suport EIP natively, but there is several ways to implement it. From my expirience, we had own EIP implementation based on Akka, but it didn't work so well. Anyway, if you want some handy DSL, there is a better idea than EIP - as it's done with GoF-patterns,...

The only difference is that a static synchronized locks on the class instance and a non-static synchronized method locks on the instance. People tell about two types of multi-threaded locking There is object instance locks and Lock style locks. A Lock, confusingly, has both. object and class Not true as...

According to JDK7 Javadoc: Retrievals reflect the results of the most recently completed update operations holding upon their onset. This means get() will return null if it was invoked before put() completed. The short answer to your question is: put() will return null....

Lets take a thread dump: "[email protected]" prio=5 tid=0xe nid=NA waiting java.lang.Thread.State: WAITING at java.lang.Object.wait(Object.java:-1) at java.lang.Object.wait(Object.java:502) at com.boris.testbench.App.lambda$main$0(App.java:22) at com.boris.testbench.App$$Lambda$1.1330278544.run(Unknown Source:-1) at java.lang.Thread.run(Thread.java:745) Line 22 in my code is lock.wait() for the top thread (A), the sequence of events: A prints "A:50" A notifies all A waits on lock B...

When creating a new instance of JavaExternClass, you're creating a new instance JavaTestForm...how this hasn't ended in a StackOverflowException is beyond me at the moment, but the "other" problem is, the instance of JavaTestForm in JavaExternClass has no relevance to the one create in main which is actually the UI...

Thread.join() waits for the thread to completely finish, whereas a synchronized block can be used to prevent two threads from executing the same piece of code at the same time. It's hard to advise when to use one over the other in general, since they serve different purposes. It's rare...